A new method uses an MRI to show how sending an electric impulse to the vagus nerve could successfully correct stomach complications. The technique could lead to more precise treatment that drugs and dietary changes have not been able to accomplish.

More than 60 million people in the US suffer from disorders in the gastrointestinal tract that electrical stimulation could cure.

“Eventually, by asking a patient to undergo multiple MRI scans with different electrical stimulation settings, we could figure out the best stimulation setting for alleviating that particular patient’s symptoms,” says Kun-Han “Tom” Lu, a PhD student in electrical and computer engineering at Purdue University.

The new MRI technique helps scientists to understand how the stomach responds to vagus nerve stimulation, which could offer more precise treatment for digestive disorders. (Credit: Purdue/Kun-Han Lu)

One important indicator of digestive disorders, which create a medical burden of billions of dollars every year, is the rate of “gastric emptying”—or how the stomach empties of food into the small intestine for the absorption of nutrients. Slow gastric emptying in the disorder gastroparesis, for example, means that stomach muscles aren’t moving properly.

Stimulating the vagus nerve would allow doctors to control how fast the stomach empties, effectively curing gastroparesis.

A better view

“Some stimulation protocols for the stomach in humans already have FDA approval, but they’ve proved only partially effective,” says Terry Powley, professor of neuroscience at Purdue University and the director of the SPARC (Stimulating Peripheral Activity to Relieve Conditions) project, an initiative of the National Institutes of Health to map out the stomach’s neural circuitry.

As part of the SPARC project, researchers proposed using MRIs in small animals to get a better view of the effects of vagus nerve stimulation on the stomach.

“MRIs are non-invasive, show tissue contrast well, and make it easier to repeat an experiment for verification,” Lu says.

Fine-tuned treatments

For the study, Lu stimulated the vagus nerve to control the pyloric sphincter in rats, the valve that controls food leaving the stomach and entering the small intestine, and then created 3D reconstructions of MRI images over time.

The images showed that stimulation relaxed the pyloric sphincter, speeding up gastric emptying to potentially correct delayed emptying in the case of gastroparesis, or other kinds of gastrointestinal malfunction.

“This method provides the physiological information for understanding the impacts of any treatment so that it can be fine-tuned for a specific organ or a specific disorder,” says Zhongming Liu, assistant professor of biomedical engineering and electrical and computer engineering.

The researchers plan to push the technology to retrieve even more information about gastric physiology and conduct their own tests of different treatments on gastric disorders.